To see other variants and accessories, please enter the webcode on our website. webcode 277 KNOWLEDGE MACHINE PREPARATION OF LABORATORY GLASSWARE When machine-cleaning laboratory glassware, you need to choose a cleaning system which is capable of adequately removing contamination for the use to which the glassware is put. The cleaning system is comprised of the laboratory washing machine, load carriers and the cleaning program. Lab washers The choice of lab washer is based on criteria such as: capacity/charge or the quantity of glassware per day, available space, type of installation (undercounter or free-standing), separation of clean and unclean sides, control program options, etc. Load carriers To load the glassware in the lab washer, mobile units, baskets and inserts are required. The geometry of the glassware (diameter of opening, diameter of body, height of the glassware) will decide whether it can be cleaned and rinsed using injection nozzles or rotating spray arms. Mobile units, baskets and inserts fitted with injection nozzles are required for narrownecked glassware, e.g. volumetric flasks, round-bottomed flasks and narrow-necked Erlenmeyer flasks. The injection nozzles project into the glassware and guarantee thorough internal cleaning, rinsing and drying. The machine's rotating spray arms clean and rinse the glassware externally. Pipettes are placed in sleeves so that, during the washing/rinsing cycles, water is fed from bottom to top, and for the drying cycle, hot air is fed likewise from bottom to top. Beakers, Petri dishes, wide-necked Erlenmeyer flasks and test tubes are placed in special inserts. These are then placed in the upper and lower baskets. The spray arms on the upper basket and in the machine ensure that glassware is cleaned and rinsed both inside and out. Cleaning programs The aim of cleaning is to remove contamination adequately from the glassware for the use to which it is put. Therefore it is particularly important when selecting a cleaning program and cleaning agents to have an understanding of the physical and chemical properties of the contamination. The physical and chemical properties of the contamination include e.g. solubility in water (pH 2-7-13), chemical change as a result of hydrolysis or oxidation, the melting or deformation point, potential for emulsification, etc. Any cleaning program consists of several cycles. The UNIVERSAL Program runs as follows: cold pre-rinse, hot alkaline wash, acid neutralization, 1-2 rinses, hot final rinse and drying. This program is suitable for removing water soluble residues and a variety of organic contamination. For cell and tissue cultures, an oxidizing agent based on hydrogen peroxide or hypochlorite should be added during the alkaline wash cycle. For laboratory glassware which is soiled and even heavily soiled with grease and paraffin wax (food and petro-chemical industries), the ORGANIC Program works well, as it includes two hot alkaline washes at higher temperatures compared to UNIVERSAL Program. Due to the double hot alkaline wash, the amount of grease and paraffin wax can be better transported from the lab washer. During the first cleaning, an emulsifier can be additionally dosed to emulsify the organic residues. With inorganic contamination (e.g. metal salts) the INORGANIC Program is preferable, which includes a hot acid pre-wash before the alkaline wash in comparison to UNIVERSAL Program. Acids such as citric acid and phosphoric acid can be used. Author: Dr. rer. nat. Roy Schneider
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